Rotating Electrical Machine Rotor Manufacturing Method and Rotating Electrical Machine Rotor

This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2024-046501, filed on Mar. 22, 2024, the entire content of which is incorporated herein by reference.

This disclosure relates to a rotating electrical machine rotor manufacturing method, and a rotating electrical machine rotor.

A known rotating electrical machine rotor manufacturing method and a known rotating electrical machine rotor are disclosed in JP 2014-147142 A. There is known a technique of injection-molding a material for a bonded magnet obtained by mixing a magnetic material (magnetic powder) and a non-magnetic resin material (binder) in magnet arrangement holes in a rotor core.

Meanwhile, if an axial length of a rotor core is relatively long, the axial length (flow length) at a time of injection-molding the bonded magnet is correspondingly long, making it difficult to form the bonded magnet.

Therefore, in one aspect, an object of this disclosure is to make it possible to form a bonded magnet with good quality even if an axial length of a rotor core is relatively long.

A need thus exists for a rotating electrical machine rotor manufacturing method and a rotating electrical machine rotor which are not susceptible to the drawback mentioned above.

In one aspect, there is provided a rotating electrical machine rotor manufacturing method including

Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings. Note that dimension ratios in the drawings are merely examples and are not limited thereto, and shapes and the like in the drawings may be partially exaggerated for convenience of description. Furthermore, in the drawings, simply some of a plurality of parts having the same attribute may be denoted by reference signs for the sake of clarity.

Hereinafter, two embodiments will be also referred to as a first embodiment and a second embodiment, and will be described in order from the first embodiment.

is a schematic view showing a rotating electrical machine rotor manufacturing apparatusaccording to a first embodiment.shows a rotating electrical machine rotor manufacturing apparatusin a cross-sectional view taken along a plane passing through a central axis IO. However, an injection molding machineis schematically shown in a form of a block diagram.

shows a trimetric view in which three axes cross at right angles to each other in a right-handed coordinate system (similar applies to followingand the like). In the following description, directions may be appropriately represented in a trimetric view. In the following description, a Z direction is a vertical direction, and a positive Z direction is assumed to be on an upper side. An XY plane is assumed to be a horizontal plane. An X direction is assumed to be a direction parallel to the central axis IO, and is also referred to as an axial direction. Assuming a cylinder having the central axis IO as a central axis thereof, terms “radial direction” and “circumferential direction” correspond to a radial direction and circumferential direction of the cylinder.

The rotating electrical machine rotor manufacturing apparatusincludes a molding device, the injection molding machine, and a robot hand.

The molding deviceincludes a movable mold, a fixed mold, an oriented magnetic field application device, a centering mechanism, an ejector pin, a movable spacer, and a slide spacer.

The movable moldand the fixed moldcan be opened and closed in the X direction. In a modification, a molding device that can be opened and closed in the vertical direction may be used.

The fixed moldmay incorporate a gate or runner for injection molding. In this case, the fixed moldforms an injection molding device together with the injection molding machinedescribed later.

The injection molding device allows the oriented magnetic field application deviceto act on a bonded-magnet material injected into a magnet arrangement hole of a rotor core. The oriented magnetic field application devicecan apply an oriented magnetic field to a set workpiece W (described later) of the rotor core. The oriented magnetic field acts on the bonded-magnet material injected in an injection molding step described later. That is, the oriented magnetic field has a role of orienting a magnet component in the bonded-magnet material and causing a cured material of the bonded-magnet material after curing to function as a permanent magnet (bonded magnet). Here, an axial length of an effective area of the alignment magnetic field by the oriented magnetic field application deviceis assumed to be the same as an axial length L of the oriented magnetic field application devicein the drawing. The oriented magnetic field application deviceis disposed around the central axis IO. The oriented magnetic field application devicemay be provided integrally with the movable mold. That is, the movable moldmay support the oriented magnetic field application deviceso as to be integrally movable with the oriented magnetic field application device.

The centering mechanismhas a function of centering the workpiece W (described later) with respect to the central axis IO. The centering mechanismmay have a cylindrical shape having an outer diameter corresponding to an axial hole (described later) of the workpiece W. In this case, the centering mechanismcan center the workpiece W with respect to the central axis IO by passing through the axial hole of the workpiece W. The centering mechanismmay be provided integrally with the movable mold. That is, the movable moldmay support the centering mechanismso as to be integrally movable with the centering mechanism.

The ejector pinmay be a mechanism originally provided in the molding device. The ejector pinis movable in the axial direction with respect to the movable mold. The ejector pinfunctions, for example, when the workpiece W is removed from the movable mold.

The movable spacerfunctions as an axial spacer. The movable spaceris movable in the axial direction with respect to the centering mechanism(accordingly, the movable mold) while being centered by the centering mechanism. The movable spacermay have an annular shape in an axial view. A function of the movable spacerwill be described later in connection with description of a manufacturing method described later.

Similarly to the movable spacer, the slide spacerfunctions as an axial spacer. The slide spaceris disposed at a position out of an axial range of the oriented magnetic field application device. The slide spaceris movable in the radial direction with respect to the movable mold. The slide spacermay be axially fixed to the movable mold. A function of the slide spacerwill be described later in connection with description of a manufacturing method described later.

Next, a rotating electrical machine rotor manufacturing method according to the present embodiment, the method using the rotating electrical machine rotor manufacturing apparatus, will be described with reference to.

is a schematic flowchart showing a flow of the rotating electrical machine rotor manufacturing method according to the present embodiment.are explanatory views of each state in this manufacturing method.is a side view of a workpiece W.andare side views showing a relation between the rotating electrical machine rotor manufacturing apparatusand the workpieces W in a side view similar to.is an explanatory view of the slide spacer, and is a view showing two states (positions) of the slide spacerin the axial view.is a view showing another variation of the slide spacer.

This manufacturing method first includes a step of providing two workpieces W for forming one rotor core (Step S). In the present embodiment, one rotor core(refer to) is formed by bonding two core parts in the axial direction (described later). The two workpieces W correspond to two core parts. Hereinafter, the two workpieces W are referred to as half cores Wand Wwhen distinguished from each other. The half cores Wand Whave identical configurations, but may have different configurations (for example, may have different axial lengths) in the modification.shows an example of a workpiece W in the cross-sectional view. The workpiece W includes an axial holeW corresponding to an axial hole(refer to) of the rotor coreand a magnet arrangement holeW corresponding to a magnet arrangement hole(refer to) of the rotor core.

Next, this manufacturing method includes a step of setting a first half core Won the molding device(Step S).shows explanatory views of this step in a chronological order from top. The half core Wis gripped by the robot hand(ST) and transferred to the molding device(refer to arrow R). Then, the half core Wis set on the molding deviceso as to be centered by the centering mechanism(ST). That is, the robot handis centered by the centering mechanism, by pushing the half core Win a negative X direction (refer to arrow R). Thus, the central axis IO of the centering mechanismand a central axis Iof the half core Wcoincide with each other. At this time, the half core Wis set on the molding devicewhile no bonded magnet is formed in the magnet arrangement holeW (that is, the magnet arrangement holeW is empty). Thereafter, the robot handretracts in a direction away from the movable mold(refer to arrow R) after releasing the half core W(ST).

Next, this manufacturing method includes a step of forming a closed mold state of the molding devicewhile the first half core Wis set (Step S). In this case, when the movable moldmoves in a positive X direction (refer to arrows Rto R), a closed mold state (ST) is formed from an open mold state (STin) through an intermediate state ST. In the closed mold state (ST), the half core Wis axially sandwiched between the movable moldand the fixed moldvia the movable spacerand the slide spacer.

Next, this manufacturing method includes a bonded-magnet molding step for the first half core W(Step S). The bonded-magnet molding step may be performed in a state where mold clamping force is generated. This step is achieved by injection-molding a material for the bonded magnet (hereinafter, also simply referred to as a “bonded-magnet material”) obtained by mixing magnetic powder and a binder, by using the injection molding machineand the gate in the fixed mold. A method for the injection molding is arbitrary, and may include, for example, transfer molding, resin injection by compression molding using a cylinder, and the like. The runner may be of any type such as a cold runner type or a hot runner type. The magnet arrangement holeW of the half core Wis filled with the bonded-magnet material.shows a bonded-magnet materialthat fills the half core W(refer to arrows R). The bonded-magnet materialcontains, for example, a thermoplastic resin material, and when the magnet arrangement holeW of the half core Wis filled with the bonded-magnet material, the bonded-magnet material is gradually cured.

The bonded-magnet molding step for the first half core W(Step S) is performed in a state where the oriented magnetic field is formed by the oriented magnetic field application device. In the bonded-magnet molding step for the first half core W(Step S), the first half core Wis positioned in the oriented magnetic field of the oriented magnetic field application device. That is, the half core Wis disposed in a space surrounded by the oriented magnetic field application device(in a cylindrical space having a length L).

Next, this manufacturing method includes a step of forming the open mold state (Step S). The open mold state is achieved by moving the movable moldin the negative X direction together with the half core Wfilled with the bonded-magnet materialas denoted by the arrows Rin.

In the present embodiment, this step (Step S) is preferably performed quickly after the bonded-magnet molding step for the first half core W(Step S). That is, this step (Step S) is preferably performed before the bonded-magnet materialis cured. Thus, it is possible to minimize time between the bonded-magnet molding step for the first half core W(Step S) and a bonded-magnet molding step for the subsequent second half core W(Step S). This technical significance will be described later in connection with the bonded-magnet molding step for the subsequent second half core W(Step S).

Next, this manufacturing method includes a next step of moving the slide spacerto retracted positions on radially outer sides (Step S). This step is achieved by sliding the slide spacerto the retracted positions on the radially outer sides (for example, the vertical direction) as denoted by the arrows Rin. Movement of the slide spacermay be achieved by any actuator or may be achieved by using a robot hand such as the robot hand.shows on the left side a state (spacer position) in which the slide spacerfunctions as a spacer, and shows on the right side a state (retracted positions) in which the slide spacerdoes not function as a spacer. In the example shown in, the slide spacerhas divided partsandthat can be separated horizontally in the axial view. The divided partsandcome into contact with each other in a horizontal direction at the spacer position. In this case, mating surfaces (contact surfaces) correspond to the XY plane. However, the mating surfaces are determined according to the sliding direction, and may be any surface including the axial direction. When mated, the divided partsandhave a circular shape in the axial view. When mated, the divided partsandform an axial holethrough which the centering mechanismpasses. The slide spacermay further include an engaging means for engaging the divided partsand. As shown in, the engaging means may be a means for fitting a projectionto a recess (or a hole)in the horizontal direction. By being moved in directions in which they separate from each other, the divided partsandcan move from the spacer position to the retracted positions to change states thereof (refer to arrow R). By being moved in directions in which they approach each other, the divided partsandcan move from the retracted positions to the spacer position to change states thereof. A structure of the slide spacershown inis merely an example, and various changes can be made. For example, divided partsA andA having a non-circular shape in the axial view when mated, such as a slide spacerA shown in, may be used.

Next, this manufacturing method includes a step of setting the second half core Won the molding device(Step S). Similarly to the first half core W, the second half core Wis set on the molding devicewhile no bonded magnet is formed in the magnet arrangement holeW (that is, the magnet arrangement holeW is empty). In this set state, the half core Wand the half core Ware adjacent to each other in the axial direction. Phases of each magnet arrangement holeW of the half core Wand each magnet arrangement holeW of the half core Ware matched with each other. That is, each magnet arrangement holeW of the half core Wand each magnet arrangement holeW of the half core Woverlap each other in the axial view. In a modification, a slight shift may be positively set between the phase of each magnet arrangement holeW of the half core Wand the phase of each magnet arrangement holeW of the half core W. That is, each magnet arrangement holeW of the half core Wand each magnet arrangement holeW of the half core Wmay partially overlap each other in the axial view. In this case also, each magnet arrangement holeW of the half core Wand each magnet arrangement holeW of the half core Wmay be connected to each other in the axial direction (communicate with each other when there is no bonded-magnet material).schematically shows with the arrow Rand Rmovement from a state in which the half core Wis gripped by the robot hand(ST) to a state (ST) in which the half core Wis set.

Next, this manufacturing method includes a step of forming the closed mold state of the molding devicewhile the second half core Wis set (Step S). As denoted by the arrow Rin, the closed mold state can be achieved by moving the movable mold, in which the half core Wand the half core Ware set, in the positive X direction to a position at which the movable moldis fit to the fixed mold.

Next, this manufacturing method includes a bonded-magnet molding step for the second half core W(Step S). This step may be performed similarly to the bonded-magnet molding step for the first half core Was described above (Step S). The magnet arrangement holeW of the half core Wis filled with the bonded-magnet material.shows a bonded-magnet materialthat fills the half core W(refer to arrows R). A material of the bonded-magnet materialis identical to a material of the bonded-magnet material.

The bonded-magnet molding step for the second half core W(Step S) is preferably performed in a state where the first half core Wand half core Wdescribed above are adjacent to each other in the axial direction. Accordingly, the bonded-magnet materialcan come into contact with the bonded-magnet materialbefore, during, or after curing. Thus, thereafter, when each of the bonded magnet materialand the bonded magnet materialis (completely) cured, both are substantially joined. Note that, in a case where the bonded-magnet materialcomes into contact with a cured material of the bonded-magnet material, the bonded-magnet materialmay melt by an end surface thereof (an end surface on a side in contact with the bonded-magnet material) receiving heat due to heat of the bonded-magnet material. Accordingly, even in a case where the bonded-magnet materialmelts in this manner, the bonded-magnet materialand the bonded-magnet materialare substantially joined to each other at the time when both the bonded-magnet materials are cured. Hereinafter, the half core Wand the half core Wbonded to each other via the bonded-magnet materialand the bonded-magnet materialin this manner are also referred to as an “integrated core from the two half cores Wand W”.

The bonded-magnet molding step for the second half core W(Step S) is performed in a state where the oriented magnetic field is formed by the oriented magnetic field application device. In the bonded-magnet molding step for the second half core W(Step S), the second half core Wis positioned in the oriented magnetic field of the oriented magnetic field application device. In the present embodiment, although the axial length L of the oriented magnetic field application deviceis shorter than an axial length of the integrated core from the two half cores Wand W, the second half core Wcan be positioned in the oriented magnetic field of the oriented magnetic field application device. This is because when the slide spacermoves to the retracted positions, the half core Wcan move by an axial length of the slide spacer, axially outward (toward the movable mold) from a space of the oriented magnetic field. In this case, it is possible to downsize the oriented magnetic field application device(and accordingly the rotating electrical machine rotor manufacturing apparatus) in the axial direction.

Next, this manufacturing method includes a step of forming the open mold state (Step S). As denoted by the arrows Rin, the open mold state is achieved by moving the movable moldin the negative X direction, together with the integrated core from the two half cores Wand W.

Next, this manufacturing method includes a step of extruding the integrated cores from the two half cores Wand Wwith the ejector pin(described as “EJ pin” in) (Step S). Thus, as denoted by the arrow Rin, at least a portion of the integrated core from the two half cores Wand Wis extruded out of the movable mold.

Next, this manufacturing method includes a step of removing the integrated core from the two half cores Wand Wwith the robot hand(Step S). As shown in, as denoted by the arrow, the robot handapproaches the movable moldfrom the positive X direction (arrow R) and grips the half core W(ST). Then, the integrated core from the two half cores Wand Wcan be removed by the robot handmoving in a direction away from the movable mold(arrow R) (ST).

Thereafter, as denoted by the arrows Rand Rin, when the ejector pinreturns to an original position thereof and the slide spacerreturns to the spacer position, the rotating electrical machine rotor manufacturing apparatusreturns to a prepared state for a subsequent new workpiece W (state in which a process from step Scan be started).

Here, as described above, if the axial length of the rotor core is relatively long, the axial length (flow length) at a time of injection-molding the bonded magnet is correspondingly long, making it difficult to form the bonded magnet.

In this regard, according to the present embodiment, the bonded-magnet material can be injection-molded separately for the two half cores Wand Wdisposed to overlap each other in the axial direction. Therefore, the axial length (flow length) of one workpiece W can be relatively shortened.

A bonded magnet (resin component) contracts after molding. Therefore, in a configuration in which simply the bonded-magnet material is injection-molded separately for two half cores and the two half cores are bonded in the axial direction after being cured, an axial gap is easily formed between bonded magnets of the two half cores. Generation of such an axial gap causes a decrease in strength and torque.

In this regard, according to the present embodiment, as described above, in a state where the second half core Wis disposed adjacent to the first half core Wfilled with the bonded-magnet material, the second half core Wis filled with the bonded-magnet material. Thus, even if the bonded-magnet materialof the first half core Wcontracts or is cured before the second half core Wis filled with the bonded-magnet material, the bonded-magnet materialthat fills the second half core Wcan reach the recess or the like that may be formed by the contraction. As a result, an axial gap is less likely to be generated in the integrated core from the two half cores Wand W, and a high-quality bonded magnet can be formed. Similar applies to a case where the first half core Wis temporarily removed and set again while being adjacent to the half core W(a case of a modification not shown). In this case also, the bonded-magnet materialthat fills the second half core Wcan reach a recess, such as a gate mark, on the first half core W. As a result, an axial gap is less likely to be generated in the integrated core from the two half cores Wand W, and a high-quality bonded magnet can be formed.

In the present embodiment, the bonded-magnet molding step for the second half core W(Step S) is preferably performed before the bonded-magnet material, which fills the first half core Win the bonded-magnet molding step (Step S) described above, is completely cured. This facilitates bonding between the bonded-magnet materialand the bonded-magnet material, allowing the bonded-magnet materialand the bonded-magnet materialto be more firmly bonded to each other. That is, a bonded magnet of the rotor corecan be formed such that a gap or the like is not substantially generated at a joint portion between an axial end surface (an end surface on a positive X-direction side) of the bonded-magnet materialand an axial end surface (an end surface on a negative X-direction side) of the bonded-magnet material. Furthermore, it is possible to homogenize magnet composition between the bonded-magnet materialand the bonded-magnet material.

Next, the second embodiment will be described with reference toand subsequent drawings. In the following description of the second embodiment, components that may be similar to those of the first embodiment described above are denoted by the same reference signs, and description thereof may be omitted.

is a schematic view showing a rotating electrical machine rotor manufacturing apparatusA according to the second embodiment.shows the rotating electrical machine rotor manufacturing apparatusA in a cross-sectional view taken along a plane passing through a central axis IO. However, an injection molding machineis schematically shown in a form of a block diagram.is an explanatory view of a modification of the second embodiment, schematically showing a cross-sectional view similar to.is an explanatory view of a movable spacerA, showing movement (each state) of the movable spacerA in an axial view.are explanatory views each showing, along with an explanatory view of movement of a robot handwith respect to the movable spacerA, another modification of the movable spacerA.

The rotating electrical machine rotor manufacturing apparatusA according to the present embodiment is different from the rotating electrical machine rotor manufacturing apparatusaccording to the first embodiment described above, mainly in that the molding deviceis replaced with a molding deviceA.

The molding deviceA according to the present embodiment is different from the molding deviceaccording to the first embodiment described above in that the movable mold, the fixed mold, the oriented magnetic field application device, the centering mechanism, and the movable spacerare replaced with a movable moldA, a fixed moldA, an oriented magnetic field application deviceA, a centering mechanismA, and the movable spacerA, respectively. The molding deviceA is different from the molding deviceaccording to the first embodiment described above in that a slide spaceris not included and a temporary receiving partA is added.

The movable moldA is the same in functions as the movable moldaccording to the first embodiment described above, but has formal differences due to differences regarding other components described above (for example, including or not including the slide spacer).

The fixed moldA is also the same in functions as the fixed moldaccording to the first embodiment described above, but is different in having a relief holeA to avoid interference with the temporary receiving partA in a closed mold state. Note that, in a case where the temporary receiving partA is detachable, the relief holeA may not be formed.